A teenager who sparked a debate about body image after publishing a photograph of herself in her underwear online, has spoken about reactions both positive and negative after the image went viral.

Stella Boonshoft, 18, from New York City who is a U.S. size 12, says she was overwhelmed by the huge reaction to her photo, which has been viewed over 4million times since she posted it on Tumblr last week.

She told the Today show: 'I got an outpouring of love, like pretty much instantly, but it was also extremely overwhelming because I made myself so vulnerable on the internet. It's a one-way conversation with people.'

Positive attitude: Stella Boonshoft, pictured on the Today show this morning, sparked a debate about body image after posting a photograph of herself in her underwear online

Stella, a student at NYU, admitted that there were some negative responses too, though she has learned how to handle it.

'I think that, you know, people being cruel, it doesn't really get to me because I have to remind myself I have a real life and I have real people who support me.'

She adds that she can understand where some of the criticism, however misguided, comes from.

'You know, I think people are cruel because they are uncomfortable with seeing images of someone who, you know, is not thin, and they also don't understand what the body acceptance movement is,' she explains.

'I wanted to give a message to the bullies who had tormented me and show them that it didn't work'

'It's not to promote being unhealthy. I's not to promote anything like that. It's to take away stigma of overweight people in America because, you know, a lot of us are, and – and that's all right. It doesn't mean that you can look at someone and know what is wrong with their health.'

Stella, who admits she never expected her image to generate so much attention, says she first published the image as part of Tumblr's positive body image movement.

'I finally came to a place where I was really happy with the way I looked… and I wanted to, you know, give a message to the bullies who had tormented me and show them that it didn't work.'

Sparking debate: The 18-year-old, from New York City who is a U.S. size 12, says she was overwhelmed by the huge reaction to her photo, which has been viewed over 4million times since she posted it on Tumblr

She explained: 'We don't have the authority to go judge other people's beauty, and we don't have the authority to make, you know, assumptions about other people's health based on the way they look.'

Stella originally posted the picture on her Tumblr account, before it was picked up by photographer Brandon Stanton and published on his photography site Humans of New York.

'Every day I'm bombarded with images of half-naked women, and they all look the same. God forbid we put someone like me, a size 12 on billboards'

The image came to be posted after Stella spotted Mr Stanton on the street and asked if she could take a picture of him. In return, he asked to take a picture of her – and later posted the picture of her in her underwear alongside his own photo of her.

Stella admitted that her first reaction was to 'burst into tears' when thousands of people started looking at her picture and she contemplated taking it down.

She decided to leave the picture online, where the overwhelming majority of comments have been supportive.

She told Today: 'Every single day I'm bombarded with images of half-naked women, and they all look the same. They all have the same kind of body type, and somehow that's okay, but, you know, God forbid we put someone like me, who is a size 12 on the billboards.'

'THIS IS MY BODY, DEAL WITH IT': STELLA BOONSHOFT IN HER OWN WORDS

Proud: Stella Boonshoft explained that she posted the picture in response to everyone who has ever bullied her over her size

WARNING: Picture might be considered obscene because subject is not thin. And we all know that only skinny people can show their stomachs and celebrate themselves. Well I’m not going to stand for that. This is my body. Not yours. MINE. Meaning the choices I make about it, are none of your f****** business. Meaning my size, IS NONE OF YOUR F****** BUSINESS.

If my big belly and fat arms and stretch marks and thick thighs offend you, then that’s okay. I’m not going to hide my body and my being to benefit your delicate sensitivities.

This picture is for the strange man at my nanny’s church who told me my belly was too big when I was five.

This picture is for my horseback riding trainer telling me I was too fat when I was nine.

This picture is for the girl from summer camp who told me I’d be really pretty if I just lost a few pounds

This picture is for all the f****** stupid advertising agents who are selling us cream to get rid of our stretch marks, a perfectly normal thing most people have (I got mine during puberty)

This picture is for the boy at the party who told me I looked like a beached whale.

This picture is for Emily from middle school, who bullied me incessantly, made mocking videos about me, sent me nasty emails, and called me “lard”. She made me feel like I didn’t deserve to exist. Just because I happened to be bigger than her. I was 12. And she continued to bully me via social media into high school.

MOST OF ALL, this picture is for me. For the girl who hated her body so much she took extreme measures to try to change it. Who cried for hours over the fact she would never be thin. Who was teased and tormented and hurt just for being who she was.

I’m so over that.

THIS IS MY BODY, DEAL WITH IT

Visit NBCNews.com for breaking news, world news, and news about the economy